In a method for manufacturing a glass by a float process, molten glass is continuously supplied to a horizontal bath surface of molten tin to form a ribbon-shaped glass (generally called a glass ribbon), and the glass ribbon is lifted from an exit side of a molten metal bath to draw outside the molten metal bath. The glass ribbon is then conveyed by conveying rolls (lift-out rolls) to carry in an annealing furnace and is gradually cooled while moving in the annealing furnace. The glass ribbon is cut into a necessary length by a cutting device in a next step, thereby manufacturing a sheet-shaped float glass.
The method for manufacturing a glass by a float process as described above forms one surface of a glass by a bath surface of molten metal, and forms the other surface of the glass by spreading molten glass on the molten metal. This manufacturing method makes it possible to extremely improve flatness of a glass, and is therefore known as a manufacturing method suitable for mass-production. For this reason, this float process is widely applied to the manufacturing of a sheet glass such as an automobile glass and a display glass.
FIG. 8 shows one example of the conventional apparatus for manufacturing a float glass, applied to the float process of this kind. The apparatus of this example is constituted of a float bath 101 having a molten metal bath 100 of tin, a dross box 102 provided at a downstream side of the float bath 101, and an annealing furnace 103. A plurality of lift-out rolls 105 are horizontally arranged inside the dross box 102, and a plurality of lehr rolls 106 are horizontally arranged inside the annealing furnace 103 (see Patent Document 1).
In the manufacturing apparatus shown in FIG. 8, molten glass 107 is supplied to a bath surface of the molten metal bath 100, and is drawn out into necessary thickness and width. A glass ribbon 108 thus obtained is taken out by traction force of the lift-out rolls 105, and can be conveyed to the side of the annealing furnace 103.